bigcountry

Out of my Marlin 1895 lever (post 72) with microgroove, I have been shooting IMR4198 with 300gr partition.

At 46-47gr, I get a slight bulge above the rim. With new brass (winchester) as a comparison, I get a .0054" bulge using starrett mic's. Woudl that be of concern to those who understand and look for this expansion? It is noticable. Primers look great. I am getting around 2050fps.

I need to go thru my old remington brass to see if I see the same. I did all my original load development with remington brass from 41gr-51gr. Nothing stuck out in my mind as an issue. I was told by Brian Pearce from handloader and rifle mag, that this action (1980's) can easily digest this load up to 51gr. Nosler also told me the same. But lymans and Sierra back off majorly for any leverl, post 72 or not.

I get 1.5MOA accuracy at 100 yards with 46gr, but it starts stringing vertically past that.

Roskoe

You might have a brass issue - go back and try to work up a load with the same bulletand Remington brass. Generally, a load over 2,000 fps with a 300 grain bullet is about full throttle regardless of whether someone else's rifle could load up to 51 grains with their components. I did a lot of load development with my 1895 Marlin and generally used IMR 4198. Best accuracy/consistency and my upper limit on recoil comfort came in the upper 1900's with this bullet weight. The significant bulge is a red flag.

bigcountry

Would you call .005" significant? I realize its gettin there.

Roskoe

Not really knowing how big your chamber is to begin with, a bulge of .005 from a virgin brass case may not be as big of a red flag as it is normally would be. But I would still be concerned . . . and would personally drop the load back to a level where this isn't happening. On my rifle, I also got a bulge at the web before the primers showed anything alarming. It made me wonder if that Marlin bolt was springing a little under pressure.

mossy33oak

Ive often wondered about this too, I get web expansion on my 25-06 with every shot I fire. It doesnt matter if its plain jane factory core junk or reloads. Ive just grown to expact it.

bigcountry

For regular 25-06, 270's, and 308's, etc. I worry about anything more than .004". But for 45-70 out of a lever I wasn't sure. I have a feeling the bolt isn't kicking in all the way.

bronko22000

Bigcountry - I know you are pretty knowledgeable about firearms from reading your post. But my load for my guide gun is 51 gr of H4198 behind a Hornady 300 gr interlock. I've been shooting this load for a few years without any noticable bulging of the cases. You may want to contact Marlin as you may have a chamber issue.

bigcountry

I am knowledgeable about bolts but not lever. Its a totally new world to me. I am going to look at all my old brass and measure it. Especially the 41gr loads. If it has the same bulge, I might get the chamber casted or send in. Could be dangerous I guess.

James B

This may be off base, but I have read that to much crimp can cause case bulging in the 45 LC and 45-70. With Black powder single shot loads, I don't crimp at all and can seat the bullets with just finger pressure. Of course this wouldn't work in the lever. However you might try less crimp if possible. Just a thought.

bigcountry

I do crimp heavy. Thanks for the thought